Image creation device

ABSTRACT

An image creation device includes: a plurality of geometry processing means for creating at least one drawing element list by performing geometry processing to express images, respectively, in parallel, said plurality of geometry processing means having at least one first geometry processing means to perform tyical geometry processing and at least one second geometry processing in cooperation with another geometry processing means; drawing means to perform drawing processing based on said drawing element list; and control means to selectively adopt a first mode which parallelizes said at least one first geometry processing means and said at least one second geometry processing means and a second mode to lead a processing result of said at least one second geometry processing means to an input of said at least one first geometry processing means.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image creation device such as anentertainment device and, more particularly, to an efficient geometryprocessing technique when a computer graphics image is created.

1. Description of the Related Art

In computer graphics, an object to be displayed is modeled by a set ofpolygons. The vertexes of the polygons are expressed by homogeneouscoordinates (x, y, z, w). The coordinates are converted according to theaspect coordinates, and the transparent transformation thereto or thelike are performed according to a distance. For example, a distantobject is converted to become small. The series of processings is calledas a “geometry processing”. The vertex coordinates obtained as a resultof the geometry processing is called as a display list (Display List:image display instruction).

The display list is sent to the drawing processing means. The drawingprocessing means draws a basic figure according to the display list in aframe memory. The drawing result is converted from a digital signal toan analog signal, and is displayed on a display unit.

Since the drawing result is updated according to a video rate every{fraction (1/60)}seconds, a moving image is displayed on a screen of thedisplay unit. A series of drawing processings by the drawing processingmeans is called “rendering processing”.

Recently, the advancement of the semiconductor technology is remarkable.Since it has become possible to integrate a frame memory and the drawingprocessing means on an LSI and, therefor, improve the renderingprocessing, performance of the geometry processing has become relativelyinsufficient. As means for solving such a disadvantage, it is effectiveto connect a plurality of geometry engines (means for executing thegeometry processing, and so forth) with the drawing processing means inparallel. In the drawing processing, there are a lot of parameters whichshould be preset, for instance, a clip area and a half transparentprocessing rate, etc. Thus, it becomes necessary to switch theparameters (“drawing context (Graphic Context)”, or simply “context”)used in an individual geometry engine.

On the other hand, two processings with different characters may existtogether when a detailed breakdown of the geometry processing isobserved. One of them is a pure coordinate conversion processing, andanother is a behavior calculation processing. The former is a fixedgeometry processing, and the latter is an unfixed geometry processing.For example, when a game program is analyzed, calculating a behavior ofa character (“character” is not limited to man and may be applied toother objects, such as a motion of an enemy plane in a shooting game ora car in a racing game) in response to an external input, and actuallycalculating coordinate conversion and performing illumination processinghave quite different time schedules, respectively. Although it issuffient when the former calculation is concluded on a video frame unit({fraction (1/60)}seconds) basis, the latter calculation requiressynchronization with a rendering pipeline on a polygon drawing unitbasis, which is more detailed than the former calculation. Even if bothof the calculations are similar, frequent context switching is requiredto deal with the different time axis in a single processing mode and,therefor, a serious disadvantage in the real time system arises.

Since there are processes that require the coordinate conversionprocessing while calculating and processes that require the coordinateconversion processing besides the behavior calculation processing as abehavior calculation processing, it is not necessarily simple.Therefore, a mechanism, which can send the result of the behaviorcalculation processing directly to the drawing processing means or useit for the coordinate conversion again, becomes desirable.

SUMMARY OF THE INVENTION

A main subject of the present invention is to provide an image creationdevice which can cancel the above-mentioned disadvantage.

To solve the above-mentioned disadvantage, an image creation deviceaccording to the present invention is characterized by comprising: aplurality of geometry processing means to create a drawing element listby performing geometry processings to express images, respectively, inparallel, said plurality of geometry processing means having at leastone first geometry processing means to perform a typical geometryprocessing and at least one second geometry processing means to performan atypical geometry processing with close-coupled and in cooperativewith other geometry processing means; drawing means to perform a drawingprocessing based on said drawing element list; and control means toselectively adopt a first mode which parallelizes said at least onefirst geometry processing means and said at least one second geometryprocessing means for a processing of a following step and a second modeto lead a processing result of at least one second geometry processingmeans to an input of said at least one first geometry processing means.

In a first mode, at least two drawing element lists are created inparallel. In a second mode, a drawing element list, in which theprocessing result of one geometry processing means is reflected to theprocessing result of other geometry processing means, is created.Thereby, the result of, for example, an atypical geometry processing(coordinate conversion result) is directly led to the latter stepprocessing in the first mode, and is supplied to the coordinateconversion again in the second mode. The efficiency improvement of theentire geometry processing can be achieved by using both of themproperty.

The control means has a function to dynamically switch one of the firstmode and the second mode to the other one thereof. As the switchreference in this case, for example, there are modes to switch accordingto the entire amount of the geometry processing executed in theplurality of geometry processing means and to switch according to thechange in the target of the geometry processing executed in theplurality of geometry processing means. As a latter example, forexample, it may be considered when the processor, which performs theatypical geometry processing, performs the retrieval of therepresentative point of the image which consists of the set in theplurality of vertex, the first mode is adopted, and is switched to thesecond mode when the retrieval ends.

Thereby, an efficient processing according to the content of thegeometry processing becomes possible.

Such an image processing device can be achieved by the computer singleunit, the cooperation of the computer and the program, the cooperationof the computer, and the semiconductor device used thereto.

As is clear from the above-mentioned explanation, according to thepresent invention, since the result of the atypical geometry processingis directly led to the drawing processing means and can be shifted tothe coordinate conversion on the way thereof, the geometry processing,which flexibly corresponds to a atypical element, becomes possible.

Since the efficiency improvement of the geometry processing can beachieved entirely and the context switch also decreases, an imagecreation device suitable by the real time system can be achieved.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is an internal configuration figure of the entertainment devicewhich becomes an embodiment of the present invention;

FIG. 2 is a figure which shows an example of an image created by acalculation processing of a second VPU;

FIG. 3 is a figure which shows an example of overlapping an imageasynchronously created with a first VPU with an image of FIG. 2 by asecond VPU when the bus to the GS is unoccupied;

FIG. 4 is an explanation figure of a concept of a geometry processing bya parallel connection according to the embodiment;

FIG. 5 is an explanation figure of a concept of a geometry processing bya serial connection according to the embodiment; and

FIG. 6A to FIG. 6C are figures which show an example form of a displaylist.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereafter, an embodiment, when an image creation device according to thepresent invention is applied to an entertainment device which createscomputer graphic image for entertainment, will be explained.

The entertainment device according to the embodiment expresses movingimages using polygons on the display unit, and outputs sound whichcorresponds to a movement of the image from the speaker according to aprogram or data recorded on an exchangeable media, for instance, CD-ROMand DVD-ROM, etc.

FIG. 1 illustrates an internal configuration of an entertainment device.This entertainment device 1 has two buses, a main bus B1 and a sub-busB2. The buses B1 and B2 are mutually connected or cut off through a businterface INT.

A main memory 11 which is constructed by a RAM (random access memory), amain DMAC (direct memory access controller) 12, an MPEG (Moving PictureExperts Group) decoder (MDEC) 13, a second vector processing device(VPU1, which is called a “second VPU”, hereinafter) 21, and a GIF(graphical synthesizer interface) 30 which functions as an arbiter ofthe first VPU 20 and the second VPU 21 are connected with the main busB1. A drawing processing means 31 (graphical synthesizer, which iscalled as a “GS”, hereinafter) is connected through a GIF 30 to a mainCPU (central processing unit) 10. The main CPU 10 is a semiconductordevice in which a microprocessor, a first vector processing device 20(VPU (vector processing unit) 0, which is called “first VPU”,hereinafter), etc. are mounted on one semiconductor chip. A CRTC (CRTcontroller) 33, which creates a video output signal, is connected withthe GS 31.

From the viewpoint of miniaturizing the device, an integrated typesemiconductor device which integrates part or all functions of the mainmemory 11, the main DMAC 12, the MPEG decoder 13, the second VPU 21, theGIF 30 and the GS 31 together with the main CPU 10 on one semiconductorchip may be used. When a semiconductor device which integrates only apart of components on the semiconductor chip, this semiconductor deviceand the remainder components are connected with the main bus B1.

When the entertainment device 1 is started, a main CPU 10 reads a startprogram from a ROM 17 on the sub-bus B2 through a bus interface INT, andexecutes the start program to operate an operating system. The main CPU10 controls a media drive 60 to read an application program and datafrom a media 61, and stores the data in the main memory 11. In addition,the main CPU 10 performs the geometry processing on three-dimensionalobject data (coordinate values etc. of the vertex of the polygon(representative point)). The three-dimensional object data may beconstructed by various data read from the media 61, for instance, aplurality of basic figures (polygons) in cooperation with the first VPU20.

In the main CPU 10, a high-speed memory, which is called as a SPR(Scrach Pad RAM) to temporarily hold a cooperative processing resultwith the first VPU 20, is provided.

The first VPU 20 has a plurality of calculation elements which calculatereal floating point numbers in parallel. That is, the main CPU 10 andthe first VPU 20 perform calculation processing which requires detailedoperations on a polygon unit basis of the geometry processing. Then, thedisplay list is created, which includes polygon definition informationof the vertex coordinate series, shading mode information, etc. obtainedby this calculation processing.

The polygon definition information includes drawing area settinginformation and polygon information. The drawing area settinginformation includes offset coordinates in the frame memory address onthe drawing area and coordinates of the drawing clipping area to cancelthe drawing when there are coordinates of the polygon at the externaldevice of the drawing area. The polygon information includes polygonattribute information and vertex information. The polygon attributeinformation specifies a shading mode, an α-blending mode, and a texturemapping mode, etc. The vertex information includes coordinates in thevertex drawing area, the coordinates in the vertex texture area, thevertex color, etc.

The second VPU 21 has the same-configuration as the first VPU 20, i.e.,it has a plurality of calculation elements which calculate real floatingpoint numbers in parallel. The second VPU 21 can create an image inresponse to the operation of the operation device 81 and operatingmatrix, for example, to create a display list having simpletwo-dimensional polygon definition information. The two-dimensionalpolygon definition information can be created using transparenttransformation to objects having simple shapes, such as buildings andcars, the parallel light source calculations, and the processing of atwo-dimensional curved surface creation etc.

Though the first VPU 20 and the second VPU 21 may have the sameconfiguration, they function as geometry engines to perform thecalculation processings on different contents, respectively. Usually,the processing of movement etc. of a character to which a complexbehavior calculation is requested (atypical geometry processing) isallocated to the first VPU 20, and processing of an object for which alot of polygon calculations (although simple calculations) arerequested, for instance, processing of a building etc. of the background(typical geometry processing) is allocated to the second VPU 21.

The first VPU 20 performs macro calculation processing insynchronization with a video rate, and the second VPU 21 is operated insychronization with the GS 31. With this configuration, the second VPU21 comprises a direct connection to the GS 31. Oppositely, the first VPU20 is closely coupled with the microprocessor in the main CPU 10 so thatcomplex processing may be readily carried out.

The image created by the calculation processing of the second VPU 21 isshown in FIG. 2, and FIG. 3 shows an example of overlapping the imageasynchronously created by the first VPU 20 with the image of FIG. 2 by asecond VPU when the bus to the GS is unoccupied.

As described above, a reason why it may be necessary to use two VPUs 20and 21 is that the usage of this device is specialized to theentertainment multimedia. A disturbance of the save of various registersand the floating point calculation pipeline may arise if it is appliedin a general-purpose application.

The display lists created by the first VPU 20 and the second VPU 21 aretransferred to the GS 31 through the GIF 30.

The GIF 30 operates as an Arbiter so that the display list created thefirst VPU 20 and the second VPU 21 do not collide when they aretransferred to the GS 31. In this embodiment, a display list having ahigher priority is sequentially examined, and the function fortransferring them from the upper display list to the GS 31 is added tothe GIF 30. The information, which indicates the priority of the displaylist, may be judged originally in the GIF 30 though it is usuallydescribed in the tag area when each of VPUs 20 and 21 creates thedisplay list.

The GS 31 stores the drawing contexts, and reads a drawing context thatcorresponds with the identification information of the image contextincluded in the display list from the GIF 30. The GS31 performsrendering processing using the drawing context, and draws the polygonsin the frame memory 32. Since the frame memory 32 can be used as atexture memory, the pixel image in the frame memory can be put on thepolygon to be drawn as a texture.

The main DMAC 12 controls the DMA transfer for each circuit connectedwith the main bus B1 and controls the DMA transfer for each circuitconnected with the sub-bus B2 according to the state of the businterface INT.

The MDEC 13 operates in parallel with the main CPU 10, and expands thedata compressed by the MPEG (Moving Picture Experts Group) method or theJPEG (Joint Photographic Experts Group) method, etc.

A sub-CPU 14 composed of the microprocessor etc., a sub-memory 15composed of the RAM, a sub-DMAC 16, a ROM 17 on which the program of theoperating system etc. are stored, a voice processing device 40 (SPU(sound processing unit)) which reads the sound data accumulated in soundmemory 59 and outputs it as an audio output, a communication controller(ATM) 50 to transmit and receive data by the public line etc., a mediadrive 60 to access the media 61 such as a CD-ROM and a DVD-ROM, and aninput part 70 are connected with the sub-bus B2. The input part 70 has aconnection terminal 71 to connect the operation device 81, a connectionterminal 72 to connect the memory card MC, a video input circuit 73 toreceive the input image data from the external device, and an audioinput circuit 74 to receive the voice data from the external device.

The sub-CPU 14 performs various operations according to the programstored on the ROM 17. The sub-DMAC controls the DMA transfer etc. foreach circuit connected with the sub-bus B2 only in a state that the businterface INT cuts off the main bus B1 and the sub-bus B2.

The entertainment device 1 of this embodiment processes a characteristicgeometry.

The geometry processing, which can be adapted to the high-speedrendering processing can be achieved by operating the first VPU 20 andthe second VPU 21 in parallel, becomes possible as mentioned-above.Here, the main CPU 10 dynamically determines (via software) whether tosend the calculation processing result from the first VPU 20 to the GIF30 directly or to send it serially to the second VPU 21.

The former mode is called as a “parallel connection” and the latter modeis called as a “serial connection”. The output of the second VPU 21 hasa path connected directly to the GIF 30 (GS 31), and performs thecoordinate conversion in synchronization with the timing of therendering processing of the GS 31. Therefore, the GS 31 never enters asuperfluous standby state.

FIG. 4 is a figure which shows a creation process of the display list bythe parallel connection of the first VPU 20 and the second VPU 21.

The three-dimensional object (X, Y, and Z coordinate series) identifiedby the “DMAtag” is coordinate-converted by each of the VPUs 20 and 21.The two-dimensional display lists identified by the “DMAtag” and the“GIFtag” are created. These display lists are merged and sent to the GIF30.

In the parallel connection, the display list is created as a calculationprocessing result by which the first VPU 20 performs cooperatively withthe microprocessor. The display list is held in the SPR and istransferred to the GS 31, through arbitration by the GIF 30, not tocollide with the display list created the second VPU 21. The displaylist created with the microprocessor and the first VPU 20 iscoordinate-converted and created by calculating the behavior of thethree-dimensional object identified by the “DMAtag”.

As an example, the created display list as mentioned above may be usedto calculate and to display the movement of a waterdrop flowing on awindshield.

In this case, the coordinate conversion of the three-dimensionalwaterdrop object is performed by calculating the behavior. Thewaterdrop, which flows on the windshield, is expressed by a set ofpolygons and the behavior calculation of each polygon is subject tocoordinate conversion processing. The display list of the flowingwaterdrop is created by the coordinate conversion by the behaviorcalculation.

FIG. 5 shows a creation process of the display list by the serialconnection.

In the serial connection, a conversion matrix is created as acalculation processing result of the first VPU 20. This conversionmatrix is held in the SPR, and the “DMAtag”, which identifies athree-dimensional object which converts coordinates, is added theretoand is transferred the second VPU 21. The second VPU 21 convertscoordinates of the three-dimensional object identified by the “DMAtag”by the conversion matrix which is transferred and creates thetwo-dimensional display list.

As an example, the created display list as mentioned above may be usedto calculate and to display the movement of a tire of a car in transit.In this case, before performing the coordinate conversion processing,the behavior of the center coordinates of the tire is calculated. Sincethe image of the tire is not deformed, the coordinate position where theentire image should be converted is determined by deciding the locationof the center coordinates of the tire. That is, the conversion matrixwhich determines the center coordinates of the tire by the behaviorcalculation may be created and the coordinate conversion of thethree-dimensional object of the tire may be performed by using thisconversion matrix.

The behavior calculation of the center coordinates of the tire iscalculated by the first VPU 20 from the position and the speed of thebody of the car, the coordinates value of the road and the peculiarspring constants, etc. As a result, the conversion matrix, whichdetermines the center coordinates of the tire, is calculated. Thisconversion matrix is held in the SPR. On the other hand, thethree-dimensional object of the tire is stored on the main memory 11.The main CPU 10 transfers the calculated conversion matrix to the mainmemory 11 and, subsequently, transfers the “DMAtag” to thethree-dimensional object of the tire to the main memory 11. Thetransferred conversion matrix and the “DMAtag” are merged in the mainmemory 11. The merged conversion matrix and the “DMAtag” are transferredto the second VPU 21. The second VPU 21 performs the coordinateconversion processing of the three-dimensional object identified by the“DMAtag” by using the transferred conversion matrix. As described above,the display list of the tire of the car in transit is created.

FIG. 6A to FIG. 6C are figures which show examples of the display listcreated by the first VPU 20 and the second VPU 21.

FIG. 6A is a display list for a three-dimensional object in which thecolor is fixed. The “GIFtag” shows a priority of the display list usedby the GIF 30 to perform the arbitration function. A “Size” shows a sizeof the display list. “R” and “G”, “B”, and “A” show the colors of thevertexes. “Vx” and “Vy”, “Vz”, “Vw”, and “VerteX” show the vertexcoordinates used to construct the three-dimensional object.

FIG. 6B is a display list for a three-dimensional object in which acolor of the normal of each vertex and a color of each vertex arechanged. “Nx” and “Ny”, “Nz”, “NW”, and “normal” show normal coordinatesfor each vertex used to construct the three-dimensional object.

FIG. 6C is a display list for a three-dimensional object in which colorsfor each vertex change. A “color” indicates the color in each vertex.

Thus, in the entertainment device 1 of this embodiment, the first VPU 20and the second VPU 21 may execute the geometry processing in either ofthe parallel (parallel connection) mode or the serial (serialconnection) mode in accordance with the software for the GIF 30 and theGS 31. These modes are dynamically switched according to the amount ofprocessing or the processing target of the entire geometry processing.Thus, the efficiency improvement of the geometry processing can beachieved. Especially, in the serial connection, the switch of the imagecontext in the previous step of the GS 31 becomes unnecessary and theoverhead in the GS 31 is avoided.

Though an example of using two VPUs 20 and 21 is shown as the geometryengine in this embodiment, the number of VPU may be three or more. Inthis case, the mode of the parallel connection becomes flexible. Forexample, a mode such that two VPUs are a parallel connection and theoutput thereof are led to the input stage of the third VPU may beachieved.

A similar processing by using other calculation processing means of thefunction equal to the VPU can be performed.

In this embodiment, an example where two kinds of geometry engines areachieved by using the main CPU 10 (including the first VPU 20) and thesecond VPU 21 is shown. The present invention has a principal objectthat at least one of the plurality of geometry processing means performsa typical geometry processing and at least another geometry processingmeans performs an atypical geometry processing (with a close-coupled andcooperative relationship with other geometry processing means to atleast one second geometry processing means of said plurality of geometryprocessing means). A program is used to construct control means toenable an execution of the drawing processing on the computer, based ona drawing element list. A plurality of geometry processing means areused to generate a display list by performing a geometry processing toexpress the images, respectively, in parallel. The control means canselectively adopt a manner in which the at least one geometry processingmeans (which performs a typical geometry processing) and the othergeometry processing means (which proforms a n atypical geometryprocessing) a re parallelized. The control means can also adopt a mannerwhich leads a result of the at least one geometry processing means(which performs the atypical geometry processing) to an input of theother geometry processing means (which performs the typical geometryprocessing). Therefore, the embodiment is not limited to theabove-mentioned embodiments.

Such a program may be recorded on the ROM 17 with the start program asmentioned above beforehand and may be recorded on the medium 61 such asabove-mentioned CD-ROM and DVD-ROM.

The image creation device according to the present invention is notlimited to the entertainment device 1 and may be similarly applied tothe same kind of image creation mechanism. The image, which becomes thetarget of the geometry processing, may not be a computer graphics imagefor the entertainment.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the present invention in its broaderaspects is not limited to the specific details, representative devices,and illustrated examples shown and described herein. Accordingly,various modifications may be made without departing from the spirit orscope of the general inventive concept as defined by the appended claimsand their equivalents.

What is claimed is:
 1. An image creation device comprising: a pluralityof geometry processing means for creating at least one drawing elementlist by performing geometry processing to express images, respectively,in parallel, said plurality of geometry processing means having at leastone first geometry processing means to perform typical geometryprocessing and at least one second geometry processing means to performatypical geometry processing in cooperation with another geometryprocessing means; drawing means to perform drawing processing based onsaid drawing element list; and control means to selectively adopt afirst mode which parallelizes said at least one first geometryprocessing means and said at least one second geometry processing meansand a second mode to lead a processing result of said at least onesecond geometry processing means to an input of said at least one firstgeometry processing means.
 2. The image creation device according toclaim 1, wherein said control means dynamically switches between saidfirst mode and said second mode according to an entire amount ofgeometry processing executed by said plurality of geometry processingmeans.
 3. The image-creation device according to claim 1, wherein saidcontrol means dynamically switches between said first mode and saidsecond mode according to a change in a target of geometry processingexecuted by said plurality of geometry processing means.
 4. The imagecreation device according to claim 3, wherein said control meansswitches to said first mode when said at least one second geometryprocessing means retrieves a representative point of an image from a setof of vertexes, and switches to said second mode when said retrievalends.
 5. The image creation device according to claim 1, wherein animage to be expressed by said geometry processing means is a computergraphic image for entertainment purposes.
 6. A method of switchinggeometry processing modes among a plurality of geometry processing meansof an image creation device to create a drawing element list byperforming geometry processing to express images, respectively, inparallel, said drawing element list being used in performing drawingprocessing, said method comprising: allocating a function to performtypical geometry processing to at least one first geometry processingmeans of said plurality of geometry processing means; allocating afunction to perform atypical geometry processing in cooperation withother geometry processing means to at least one second geometryprocessing means of said plurality of geometry processing means; andusing software to dynamically switch between a first mode whichparallelizes said at least one first geometry processing means and saidat least one second geometry processing means and a second mode to leada processing result of said at least one second geometry processingmeans to an input of said at least one first geometry processing means.7. A computer readable record medium containing a program to cause aplurality of geometry processing means to create a drawing element listby performing geometry processing to express images, respectively, inparallel, and to cause a control means to perform drawing processingbased on said drawing element list on a computer, said programcomprising: computer readable program code means for causing a computerto allocate a function to perform typical geometry processing to atleast one first geometry processing means of said plurality of geometryprocessing means; computer readable program code means for causing acomputer to allocate a function to perform atypical geometry processingin cooperation with other geometry processing means to at least onesecond geometry processing means of said plurality of geometryprocessing means; and computer readable program code means for causing acomputer to selectively adopt a first mode which parallelizes said atleast one first geometry processing means and said at least one secondgeometry processing means and a second mode to lead a processing resultof said at least one second geometry processing means to an input ofsaid at least one first geometry processing means.
 8. A semiconductordevice to cause a plurality of geometry processing means to create adrawing element list by performing geometry processing to expressimages, respectively, in parallel, and to cause a control means toperform drawing processing based on said drawing element list on acomputer, said semiconductor device comprising: means for allocating afunction to perform typical geometry processing to at least one firstgeometry processing means of said plurality of geometry processingmeans; and means for allocating a function to perform atypical geometryprocessing in cooperation with with other geometry processing means toat least one second geometry processing means of said plurality ofgeometry processing means, wherein said control means for selectivelyadopting a first mode which parallelizes said at least one firstgeometry processing means and said at least one second geometryprocessing means and a second mode to lead a processing result of saidat least one second geometry processing means to an input of said atleast one first geometry processing means.
 9. An apparatus forprocessing polygons of image objects to form a moving image, comprising:at least one first geometry processing unit operable to perform geometryprocessing on said polygons to form one or more background objects ofsaid moving image; at least one second geometry processing unit operableto perform geometry processing on said polygons to form one or moremoving objects of said moving image; a controller operable toselectively adopt first and second modes of operation, said first modeof operation obtaining parallel drawing element lists from said firstand second geometry processing units such that they may be merged toform a combined drawing element list, and said second mode of operationrouting said geometry processing result of said at least one secondgeometry processing unit to said at least one first geometry processingunit to produce a serial drawing element list; and a drawing unitoperable to render said polygons of said combined display element listinto a frame buffer.
 10. The apparatus according to claim 9, whereinsaid controller is further operable to dynamically switch between saidfirst and second modes of operation based on an aggregate geometryprocessing load among said geometry processing units such thatprocessing speed is maximized.
 11. The apparatus according to claim 9,wherein said controller is further operable to dynamically switchbetween said first and second modes of operation based on a change in atarget said geometry processing units.
 12. The apparatus according toclaim 11, wherein said controller switches to said first mode ofoperation such that said at least one second geometry processing unitmay calculate a representative point of an image object from among aplurality of vertexes, and switches to said second mode of operationthereafter.
 13. The apparatus according to claim 10, wherein when saidcontroller has selectively adopted said second mode of operation: saidat least one second geometry processing unit is further operable toperform said geometry processing to produce a coordinate conversionmatrix that is capable of operating on vertexes of said polygons toproduce moving objects of said moving image; said at least one secondgeometry processing unit is further operable to transfer said coordinateconversion matrix to said at least one first geometry processing unit;and said at least one first geometry processing unit is further operableto apply said coordinate conversion matrix to said vertexes of saidpolygons to produce said serial drawing element list.